1. Technical Field
The disclosure relates generally to integrated circuit (IC) chips, and more particularly, to design structure for an electrically tunable resistor.
2. Background Art
Thin film resistors are used in the integrated circuit (IC) chip industry. The resistance R of a rectangular sheet of material of width W, height H and thickness d is determined by the film resistivity (rho) by: R=rho*W/(H*d). Any of the above mentioned parameters can be varied to vary the resistance R.
A number of challenges exist relative to controlling the resistance. First, if different resistance values in a circuit are desired, the geometric parameters width W, height H or thickness d, and/or the material resistivity rho, must be varied. Second, tolerance variations in material resistivity rho, width W, height H and thickness d will lead to variations in resistance. Third, new variations in the resistance values derived by changing the resistor geometry require new masks to make specialty IC chips. Finally, changes in the resistance from a variation in material resistivity rho require a change of the deposition material, which is costly and limited by available deposition materials.
One approach to adjust a resistance value includes trimming resistors to change their physical dimensions. SU 1020869 is an example of this approach in which a heating pulse current is applied to the resistor prior to laser trimming.